Gas cooktop - Where's the heat?

[CH4Ohio]

It's kinda hard to tell from a picture, but I think it looks like a pretty good flame. Put that much fire under a pot and something is going to happen.

Could it be that we're trying to fix something that ain't broke?

On page one of the owner's manual for that range it plainly says "A watched pot never boils."

 

[CH4Ohio]

OK -- I'm bored.

Actually . . . I'm still curious about your appliance regulator. Your flame looks "soft". Here's a pic of one of our medium burners on high.

This is often described as a "hard blue flame".

At the same time, you should be realistic about how fast water will boil. You said you were boiling 3/4 of a 5 quart pot full of water. Lots of variables, but we can estimate . . .

3/4 x 5 = 3.75 quarts = .94 gallons

.94 gallons x 8.3 lb / gallon = 7.8 lb water

If your water is 50 degrees to start, you need to raise the water temp 212 - 50 = 162 degrees.

It takes 1 BTU to raise the temp of 1 pound of water 1 degree. We need 162 x 7.8 = 1264 BTUs.

It's often estimated that the heat transfer of a burner like this is about 30 - 40%. Again, lots of variables related to pots and materials and distance and circulation . . .

If 30% efficient, you need to burn 4213 BTUs in order to transfer 1264 BTU
If 40% efficient, you need to burn 3160 BTUs to do the same.

On a 15K/hour burner, this would take:
At 30% efficiency -- 4213 / 15,000 = .28 hour = 17 minutes
At 40% efficiency -- 3160 / 15,000 = .21 hour = 13 minutes

And this is on the biggest burner on HIGH setting. We rarely use our BIGGEST burner because it's usually too wide for the pot. Smaller burner would take longer due to lower ouput.


I was joking above about "a watched pot never boils", but obviously you're not the first person to think it took too long.

Be sure they verify that your regulator is set right.

The next time you "time how long it takes to boil water", actually check the temperature of the water before you start the clock and measure the volume of water and let's see if the result is reasonable.

 

[workinonit]

The flame being too wide for the pot is the most likely cause of the issue. I have a Wolf that has 34 different size burners running on propane. This is definitely not a problem I have. I can boil a very large SS blanching pot with probably 3 gallons of water in that amount of time.on a 25,000 BTU burner.

 

[Hay Dude]

I have a 6 burner Dacor that runs on Natty-G.
Our’s boils that much water in about 1/2 the time the OP’s takes.
It also needs cleaning….

 

[Richard]

I hate you all. I so dearly wish I had access to NG.

 

[LittleBittyBigJohn]

I hate you all. I so dearly wish I had access to NG.

I don't hate 'um. But I also wish I had that access. I got an ugly, expensive, propane tank hanging out in my backyard. I tried to get the natural gas company to run a line to my house but they said the closest trunk they had was over 4,000' away. The said it cost them $20,000 to run the last big expansion of 800'...

 

[workinonit]

Why is the propane so expensive compared to NG? I have 2 dual fuel units, 5 tons, dual fuel range and one of 2 HWHs is gas. My gas is not high in my opinion. LP is more expensive pu but LP is also 2 times more efficient. In the end it just depends on the price per unit. I'm guessing it's probably a wash.

 

[CH4Ohio]

I don't hate 'um. But I also wish I had that access. I got an ugly, expensive, propane tank hanging out in my backyard. I tried to get the natural gas company to run a line to my house but they said the closest trunk they had was over 4,000' away. The said it cost them $20,000 to run the last big expansion of 800'...

I'm on propane too. That pic I posted is the front burner on our propane cooktop.

 

[CH4Ohio]

Why is the propane so expensive compared to NG? I have 2 dual fuel units, 5 tons, dual fuel range and one of 2 HWHs is gas. My gas is not high in my opinion. LP is more expensive pu but LP is also 2 times more efficient. In the end it just depends on the price per unit. I'm guessing it's probably a wash.

LP is NOT 2 times more efficient. If you have a 94% efficient natural gas furnace and convert it to propane, it's still 94% efficient. But, to your point, if you compare the cost per BTU or THERM, etc., propane is certainly more expensive.

True that propane is more energy dense -- has 2500 BTU per cubic foot vs. NG at 1000 BTU per cubic foot. But the amount of fuel delivered to the burner is adjusted so the appliance has the same energy input. (A 100K BTU furnace consumes 100K BTU / hour whether it's using NG or propane.)

Propane isn't delivered via a pipeline network that transfers gas from the well to the burner-tip and serves hundreds of thousands at a time. Plus natural gas is more plentiful. Propane is definitely more expensive than being connected to a NG utility.

 

[workinonit]

But it would take half as much LP to produce the 94% efficiency as it would NG. No argument NG is probably cheaper overall but I'm thinking not by a lot. I can tell you if I had NG available I would be using it but I wouldn't take out my propane tank. I think once the feds have closed as many coal fired and nuke power plants as they are able you will see the price of NG become unaffordable.